How are diagonals registered in TGM 3?

So I'm finally coming to grips with the idea that my goal of building a real tgm3 arcade cabinet is a long ways off at best, and a pipe dream at worst. So long story short I saw an arcade stick on sale today (hori real arcade pro 4) and decided to get it. Previously I'd been playing texmaster with a keyboard, but now that I have e a stick, I want it set it up to be as authentic as possible.

Getting it configured and working was easy, but I'm wondering how the real game handles diagonal inputs. Are diagonal inputs simply ignored? Do they register as a horizontal and vertical input? Just a horizontal input?

In texmaster, it appears that it always registers diagonal inputs as being whichever input came first. For example, if I hold the stick right, and the push it up to the top right, the tetromino continues to move right, but does not hard drop. Likewise, if I hold down and then move the stick to the bottom right, the tetris still falls quickly, but does not move to the right. Is this how the tgm3 functions as well?

Edit: After further testing, it appears that texmaster either completely ignores diagonal inputs, or only registers them as horizontal inputs depending on whether you have the stick assigned to function as a dpad vs analog stick.

tops-game.jp is usually where you can find what they have. TGM 3 and the Type X are both out of stock, and trying to find both available at the same time is an adventure. They have TAP and TGM 1 (two variants, one with manual and some extras, other just the game).